jack kennedy was a friend of mine. senator, you're no jack kennedy. >> memorable moments, but hardly game-changers. while presidential debates can affect the outcome of an election, vice presidential debates, like this week's upcoming match-up between vice president biden and his gop challenger paul ryan, are a different animal. >> you need to be able to see that each vice presidential candidate has hit the standard of readiness. they'll be ready in an emergency in a national crisis to step into the oval office and to take the reins of the presidency. beyond that, in terms of the actual debate itself, unless there is a stark killing or stark catching moment, it rarely changes the course of the debate. >> donna brazile says the first rule here is to do no harm. >> in terms of substance, try not to break any new ground. this is an audition for 2016. this is about 2012, and the top of the ticket. >> i don't like a damn thing about him. >> biden, who participated in more than 20 debates and forums in the 2008 campaign, sai